Telbivudine-Induced Myopathy Incidentally Detected by FDG PET/CT Imaging in a Patient With History of Hepatocellular Carcinoma

Telbivudine-Induced Myopathy: Clinical Features, Histopathological Characteristics, and Risk Factors

BACKGROUND AND PURPOSE

Oral nucleos(t)ide analogs (NAs) are the mainstay treatment for chronic hepatitis B (CHB). Myotoxicity is an important extrahepatic effect related to NA treatment. Telbivudine is the NA for CHB that is frequently associated with muscle-related side effects. The risk factors for telbivudine-induced myopathy (TIM) are not yet clear.

METHODS

This study characterized the clinical, magnetic resonance images (MRI), and pathological features of 12 TIM cases. A group of telbivudine-tolerant (TT) patients with CHB who received regular telbivudine treatment during the same period without the occurrence of myopathy was collected. Demographic and clinical factors were compared between the patients with TIM and the TT controls. Factors independently associated with TIM were identified using logistic regression analysis.

RESULTS

The patients with TIM (males/females: 7/5, mean age: 57 years) developed myopathy after using telbivudine for a median period of 19.5 months. Muscle histopathology revealed abnormal proliferation, subsarcolemmal or sarcoplasmic accumulations, and ultrastructural defects of mitochondria. When compared with TT cases, patients with TIM had a lower estimated glomerular filtration rate and were more frequently positive for hepatitis B e antigen (HBeAg).

CONCLUSIONS

Mitochondrial abnormalities are characteristic histopathological features, and impaired renal function and HBeAg positivity are risk factors for TIM. Telbivudine-induced mitochondrial dysfunction and immune activation related to mitochondrial damage and HBeAg serostatus changes may underlie TIM. Constant clinical surveillance of myopathy during telbivudine treatment is needed due to the significant latency of its development. Dose adjustment for impaired renal function does not eliminate the risk of TIM occurrence.

Respiratory failure as the prominent manifestation of entecavir-associated mitochondrial myopathy: a case report

Background

Mitochondrial myopathy caused by the long-term use of nucleos(t)ide analogue in patients with chronic hepatitis B (CHB) is mostly characterized by myasthenia and myalgia. Cases with respiratory failure as the prominent manifestation and multisystem symptoms have not been reported.

Case report

We report a case of mitochondrial myopathy associated with the long-term use of entecavir for CHB. The patient was a 54-year-old male who was treated with entecavir for 9 years. During the treatment, hepatitis B virus (HBV) DNA was negative and liver function was normal. However, generalized fatigue, poor appetite, dysosmia and other discomforts gradually presented starting at the 5^th year of treatment, and respiratory failure was the prominent manifestation in the later stage of disease progression. The diagnosis was based on histopathology examination. The dysosmia, hypoxemia and digestive tract symptoms were gradually improved after withdrawal of entecavir.

Discussion

Mitochondrial myopathy is a rare side effect of entecavir and can be diagnosed by muscle biopsy. Although the incidence is extremely low, but the severe cases can lead to respiratory failure. We should receive adequate attention in clinical practice.